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New DNA tests for Down's syndrome

The risk of miscarriage among women pregnant with children suspected of having Down's syndrome could be significantly reduced by new highly accurate DNA blood tests for the condition, research suggests.

Current NHS testing for Down's, which includes a blood test and an ultrasound scan, has a 95% detection rate with a false positive rate of 5%. This means that 5% of women who are not pregnant with a Down's syndrome baby will be offered further invasive tests, which carry a 1% risk of miscarriage.

But experts from Hong Kong suggest that if these women were to take the DNA blood test instead, the need for invasive tests such as amniocentesis or chorionic villus sampling will be nearly completely eliminated.

The new tests use genetic material DNA to identify whether a foetus has the syndrome rather than relying on scans measuring the amount of fluid collecting in the back of babies' necks.

Writing in the British Medical Journal the scientists said: "If we took into consideration the results of the sequencing test, trisomy 21 (Down's) could be ruled out in 98% of those pregnancies.

"This would leave just 0.1% of all pregnant women needing referrals for amniocentesis or chorionic villus sampling."

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British Medical Journal